Everyone expected things would change when Microsoft bought the VoIP provider Skype last year. It appears that Redmond is now making Skype its own. According to security researcher Kostya Kortchinsky, Microsoft has quietly made a major change to the fundamental technology behind Skype. The old P2P supernode network is gone, replaced by a cluster of Microsoft managed servers.

In the past, Skype routed VoIP data by promoting regular users with sufficient bandwidth and processing power to so-called supernodes. It’s been that way since 2003, but Microsoft had concerns about reliability and security with this P2P approach. After all, there was a major Skype outage right after Microsoft bought the company. It looks like regular users are no longer able to become supernodes at all.

The new Skype backbone is composed of about 10,000 Linux servers. That is contrasted to nearly 50,000 p2p supernodes in the past. Kortchinsky isn’t worried about capacity, though. The new boxes should support far more connections; 4,100 versus just 800. The hardware is likely capable of routing many more users in the future; possibly as many as 100,000. Microsoft is also running the grsecurity Linux patches on the Skype hardware to prevent malicious hacking.

Skype usage has shot up since Microsoft bought the company for $8.5 billion nearly a year ago. As Redmond continues to build Skype into products like Windows Phone and Windows 8, it needed to be sure the network was up to the task. Microsoft has not confirmed the change publicly, but Kortchinsky speculates it will make businesses more receptive to using the service.